More than 100 scientists and clinicians have questioned the authenticity of a massive hospital database that was the basis for an influential study published last week that concluded that treating people who have Covid-19 with chloroquine and hydroxychloroquine did not help and might have increased the risk of abnormal heart rhythms and death.

In an open letter to The Lancet’s editor, Richard Horton, and the paper’s authors, the scientists asked the journal to provide details about the provenance of the data and called for the study to be independently validated by the World Health Organization or another institution.

A spokeswoman for Dr. Mandeep R. Mehra, the Harvard professor who was the paper’s lead author, said on Friday that the study’s authors had asked for an independent academic review and audit of their work.